R & F - Encaustic Brush - Filbert - Size 10 - R and F Encaustic Brushes meet the unique demands of encaustic painting. These high quality brushes are made from natural hair, rather than synthetic fibers to prevent melting and scorching on heated surfaces. R and F Filbert brushes are flat with domed ends. They allow good coverage and have the ability to perform some detail work. Filberts will create softer more rounded strokes because of their shape.